SeaQuarium has the only under water tunnel in North Wales, where you can walk under the waves, see sharks, rays. conger eels and witness the wonders of the ocean and other sea creatures within their natural habitats. . SeaQuarium’s “wet and wild” Sealion Cove is a specially designed marine theatre where these natural-born performers show off with front flipper walks, balancing acts, hurdle jumps – and lots of splashing in their 33,000-gallon pool.